Gastric bypass surgery halved the risk of heart failure
A new study shows that obesity links to a higher risk of heart failure.
Heart attacks and strokes get much more attention in news stories and statistics than heart failure. Often called congestive heart failure or CHF for short, this is a condition where the heart can no longer pump enough oxygenated blood to the body.
It probably should get more attention. The disease is actually more prevalent and deadly than strokes. Whereas mortality figures for heart attacks (coronary thrombosis) have decreased in the past decade, the numbers of deaths because of CHF have risen. As the average age of the population increases, the tally of such deaths will probably rise all the more.
This makes it important to try and prevent the disease.
The major causes of CHF are previous heart attacks, high blood pressure, diabetes and cardiac valve problems.
But the results of a new Swedish study point towards an additional risk factor:
Obesity.
Largest weight losses linked to operations
Indications of this link have been seen in previous studies – obese persons are more likely to suffer heart failure. But no one has been able to show that obesity can sometimes act as the sole culprit for causing CHF.
Johan Sundström, who works at Uppsala University Hospital, and colleagues have found data which leads to this conclusion.
They have compared health records from about 26,000 persons who have had gastric bypass surgery to reduce their obesity with records of about 14,000 who attempted to lose weight through intensive dieting efforts and changes in lifestyles.
As in earlier comparisons, it was seen that those who had surgery lost much more weight than the others. Patients who had the bypass surgery, which involves the removal of part of the stomach, weighed an average of 18.6 kg less than the lifestyle group after a year and 22.6 kg less after two years.
The question is: Did this difference have an impact on risk of congestive heart failure in the next four years?
Half the risk
Indeed it did.
On average, the risk of CHF among patients who had undergone gastric bypasses was half that of those who had dieted and changed their lifestyles – but not had surgery.
Sundström and colleagues also saw that the effect was linked to how much weight the persons shed: the greater the weight loss, the lower the risk of heart failure. They think these results single out obesity as one of the causes of this heart condition.
Professor Torbjørn Omland at the University of Oslo’s Institute of Clinical Medicine thinks the new study is probably the closest we can come to certitude that obesity causes heart failure. Yet he is not surprised by the results.
“We have our own data that suggests the same thing: When patients undergo gastric bypasses their biomarkers for congestive heart failure drop,” he says.
Biomarkers are measureable indicators of a biological state or condition, usually substances in the bloodstream that signal diseases or disorders.
Professor Jøran Hjelmesæth of the Vestfold Hospital Trust and the University of Oslo thinks the Swedish study is solid and intriguing. Like Omland, he is not exactly thunderstruck.
“Obesity puts a strain on the heart. Blood volume increases and the heart gets a harder job pumping it around the body.”
Hjelmesæth thinks the new study provides grounds for optimism.
“It shows that we can prevent a serious disease if we help obese persons lose weight.”
Few suffered CHF
The new results might also help change the way we view dieting and disease.
On the one hand it might undermine the notion of “fat but fit” – that extra kilos of fat don’t matter as long as a person has a healthy and active lifestyle. It could also weaken the lifestyle experts’ mantra about even a small weight reduction having a large beneficial effect on health.
Hjelmesæth points out, nevertheless, that the new study does not indicate any dramatic effect in actuality. Few cases of heart failure were seen in either group of obese persons.
In the course of the four years that the researchers followed the health records of nearly 40,000 persons, only 73 suffered congestive heart failure. The researchers have calculated that 500 obese persons need to be treated to avert a single hospitalisation for CHF.
This means that while obesity is a cause of heart failure, it certainly is not the key one.
Hjelmesæth thinks therefore that the results of the study are not likely to lead to big changes in the treatment of obesity.
Torbjørn Omland is a co-editor in Circulation, the journal in which the Swedish study was published.
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Read the Norwegian version of this article at forskning.no
Translated by: Glenn Ostling
